
package com.oahcfly.chgame.core.ui;

import java.io.InputStream;
import java.util.Vector;

import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Animation;
import com.badlogic.gdx.graphics.g2d.Animation.PlayMode;
import com.badlogic.gdx.graphics.g2d.TextureRegion;
import com.badlogic.gdx.utils.Array;

/** <pre>
 * 源自：http://www.badlogicgames.com/forum/viewtopic.php?f=11&t=10351&p=46673#p46673
 * 
 * date: 2015-1-26
 * </pre>
 * 
 * @author caohao */
public class CHGifDecoder {
	/** File read status: No errors. */
	public static final int STATUS_OK = 0;

	/** File read status: Error decoding file (may be partially decoded) */
	public static final int STATUS_FORMAT_ERROR = 1;

	/** File read status: Unable to open source. */
	public static final int STATUS_OPEN_ERROR = 2;

	/** max decoder pixel stack size */
	protected static final int MAX_STACK_SIZE = 4096;

	protected InputStream in;

	protected int status;

	protected int width; // full image width

	protected int height; // full image height

	protected boolean gctFlag; // global color table used

	protected int gctSize; // size of global color table

	protected int loopCount = 1; // iterations; 0 = repeat forever

	protected int[] gct; // global color table

	protected int[] lct; // local color table

	protected int[] act; // active color table

	protected int bgIndex; // background color index

	protected int bgColor; // background color

	protected int lastBgColor; // previous bg color

	protected int pixelAspect; // pixel aspect ratio

	protected boolean lctFlag; // local color table flag

	protected boolean interlace; // interlace flag

	protected int lctSize; // local color table size

	protected int ix, iy, iw, ih; // current image rectangle

	protected int lrx, lry, lrw, lrh;

	protected DixieMap image; // current frame

	protected DixieMap lastPixmap; // previous frame

	protected byte[] block = new byte[256]; // current data block

	protected int blockSize = 0; // block size last graphic control extension
	// info

	protected int dispose = 0; // 0=no action; 1=leave in place; 2=restore to
	// bg; 3=restore to prev

	protected int lastDispose = 0;

	protected boolean transparency = false; // use transparent color

	protected int delay = 0; // delay in milliseconds

	protected int transIndex; // transparent color index

	// LZW decoder working arrays
	protected short[] prefix;

	protected byte[] suffix;

	protected byte[] pixelStack;

	protected byte[] pixels;

	protected Vector<GifFrame> frames; // frames read from current file

	protected int frameCount;

	private static class DixieMap extends Pixmap {
		DixieMap (int w, int h, Pixmap.Format f) {
			super(w, h, f);
		}

		DixieMap (int[] data, int w, int h, Pixmap.Format f) {
			super(w, h, f);

			int x, y;

			for (y = 0; y < h; y++) {
				for (x = 0; x < w; x++) {
					int pxl_ARGB8888 = data[x + y * w];
					int pxl_RGBA8888 = ((pxl_ARGB8888 >> 24) & 0x000000ff) | ((pxl_ARGB8888 << 8) & 0xffffff00);
					// convert ARGB8888 > RGBA8888
					drawPixel(x, y, pxl_RGBA8888);
				}
			}
		}

		void getPixels (int[] pixels, int offset, int stride, int x, int y, int width, int height) {
			java.nio.ByteBuffer bb = getPixels();

			int k, l;

			for (k = y; k < y + height; k++) {
				int _offset = offset;
				for (l = x; l < x + width; l++) {
					int pxl = bb.getInt(4 * (l + k * width));

					// convert RGBA8888 > ARGB8888
					pixels[_offset++] = ((pxl >> 8) & 0x00ffffff) | ((pxl << 24) & 0xff000000);
				}
				offset += stride;
			}
		}
	}

	private static class GifFrame {
		public GifFrame (DixieMap im, int del) {
			image = im;
			delay = del;
		}

		public DixieMap image;

		public int delay;
	}

	/** Gets display duration for specified frame.
	 *
	 * @param n int index of frame
	 * @return delay in milliseconds */
	public int getDelay (int n) {
		delay = -1;
		if ((n >= 0) && (n < frameCount)) {
			delay = frames.elementAt(n).delay;
		}
		return delay;
	}

	/** Gets the number of frames read from file.
	 *
	 * @return frame count */
	public int getFrameCount () {
		return frameCount;
	}

	/** Gets the first (or only) image read.
	 *
	 * @return BufferedPixmap containing first frame, or null if none. */
	public Pixmap getPixmap () {
		return getFrame(0);
	}

	/** Gets the "Netscape" iteration count, if any. A count of 0 means repeat indefinitely.
	 *
	 * @return iteration count if one was specified, else 1. */
	public int getLoopCount () {
		return loopCount;
	}

	/** Creates new frame image from current data (and previous frames as specified by their disposition codes). */
	protected void setPixels () {
		// expose destination image's pixels as int array
		int[] dest = new int[width * height];
		// fill in starting image contents based on last image's dispose code
		if (lastDispose > 0) {
			if (lastDispose == 3) {
				// use image before last
				int n = frameCount - 2;
				if (n > 0) {
					lastPixmap = getFrame(n - 1);
				} else {
					lastPixmap = null;
				}
			}
			if (lastPixmap != null) {
				lastPixmap.getPixels(dest, 0, width, 0, 0, width, height);
				// copy pixels
				if (lastDispose == 2) {
					// fill last image rect area with background color
					int c = 0;
					if (!transparency) {
						c = lastBgColor;
					}
					for (int i = 0; i < lrh; i++) {
						int n1 = (lry + i) * width + lrx;
						int n2 = n1 + lrw;
						for (int k = n1; k < n2; k++) {
							dest[k] = c;
						}
					}
				}
			}
		}
		// copy each source line to the appropriate place in the destination
		int pass = 1;
		int inc = 8;
		int iline = 0;
		for (int i = 0; i < ih; i++) {
			int line = i;
			if (interlace) {
				if (iline >= ih) {
					pass++;
					switch (pass) {
					case 2:
						iline = 4;
						break;
					case 3:
						iline = 2;
						inc = 4;
						break;
					case 4:
						iline = 1;
						inc = 2;
						break;
					default:
						break;
					}
				}
				line = iline;
				iline += inc;
			}
			line += iy;
			if (line < height) {
				int k = line * width;
				int dx = k + ix; // start of line in dest
				int dlim = dx + iw; // end of dest line
				if ((k + width) < dlim) {
					dlim = k + width; // past dest edge
				}
				int sx = i * iw; // start of line in source
				while (dx < dlim) {
					// map color and insert in destination
					int index = ((int)pixels[sx++]) & 0xff;
					int c = act[index];
					if (c != 0) {
						dest[dx] = c;
					}
					dx++;
				}
			}
		}
		image = new DixieMap(dest, width, height, Pixmap.Format.RGBA8888);
		// Pixmap.createPixmap(dest, width, height, Config.ARGB_4444);
	}

	/** Gets the image contents of frame n.
	 *
	 * @return BufferedPixmap representation of frame, or null if n is invalid. */
	public DixieMap getFrame (int n) {
		if (frameCount <= 0) return null;
		n = n % frameCount;
		return ((GifFrame)frames.elementAt(n)).image;
	}

	/** Reads GIF image from stream
	 *
	 * @param is containing GIF file.
	 * @return read status code (0 = no errors) */
	public int read (InputStream is) {
		init();
		if (is != null) {
			in = is;
			readHeader();
			if (!err()) {
				readContents();
				if (frameCount < 0) {
					status = STATUS_FORMAT_ERROR;
				}
			}
		} else {
			status = STATUS_OPEN_ERROR;
		}
		try {
			is.close();
		} catch (Exception e) {
		}
		return status;
	}

	/** Decodes LZW image data into pixel array. Adapted from John Cristy's BitmapMagick. */
	protected void decodeBitmapData () {
		int nullCode = -1;
		int npix = iw * ih;
		int available, clear, code_mask, code_size, end_of_information, in_code, old_code, bits, code, count, i, datum, data_size, first, top, bi, pi;
		if ((pixels == null) || (pixels.length < npix)) {
			pixels = new byte[npix]; // allocate new pixel array
		}
		if (prefix == null) {
			prefix = new short[MAX_STACK_SIZE];
		}
		if (suffix == null) {
			suffix = new byte[MAX_STACK_SIZE];
		}
		if (pixelStack == null) {
			pixelStack = new byte[MAX_STACK_SIZE + 1];
		}
		// Initialize GIF data stream decoder.
		data_size = read();
		clear = 1 << data_size;
		end_of_information = clear + 1;
		available = clear + 2;
		old_code = nullCode;
		code_size = data_size + 1;
		code_mask = (1 << code_size) - 1;
		for (code = 0; code < clear; code++) {
			prefix[code] = 0; // XXX ArrayIndexOutOfBoundsException
			suffix[code] = (byte)code;
		}
		// Decode GIF pixel stream.
		datum = bits = count = first = top = pi = bi = 0;
		for (i = 0; i < npix;) {
			if (top == 0) {
				if (bits < code_size) {
					// Load bytes until there are enough bits for a code.
					if (count == 0) {
						// Read a new data block.
						count = readBlock();
						if (count <= 0) {
							break;
						}
						bi = 0;
					}
					datum += (((int)block[bi]) & 0xff) << bits;
					bits += 8;
					bi++;
					count--;
					continue;
				}
				// Get the next code.
				code = datum & code_mask;
				datum >>= code_size;
				bits -= code_size;
				// Interpret the code
				if ((code > available) || (code == end_of_information)) {
					break;
				}
				if (code == clear) {
					// Reset decoder.
					code_size = data_size + 1;
					code_mask = (1 << code_size) - 1;
					available = clear + 2;
					old_code = nullCode;
					continue;
				}
				if (old_code == nullCode) {
					pixelStack[top++] = suffix[code];
					old_code = code;
					first = code;
					continue;
				}
				in_code = code;
				if (code == available) {
					pixelStack[top++] = (byte)first;
					code = old_code;
				}
				while (code > clear) {
					pixelStack[top++] = suffix[code];
					code = prefix[code];
				}
				first = ((int)suffix[code]) & 0xff;
				// Add a new string to the string table,
				if (available >= MAX_STACK_SIZE) {
					break;
				}
				pixelStack[top++] = (byte)first;
				prefix[available] = (short)old_code;
				suffix[available] = (byte)first;
				available++;
				if (((available & code_mask) == 0) && (available < MAX_STACK_SIZE)) {
					code_size++;
					code_mask += available;
				}
				old_code = in_code;
			}
			// Pop a pixel off the pixel stack.
			top--;
			pixels[pi++] = pixelStack[top];
			i++;
		}
		for (i = pi; i < npix; i++) {
			pixels[i] = 0; // clear missing pixels
		}
	}

	/** Returns true if an error was encountered during reading/decoding */
	protected boolean err () {
		return status != STATUS_OK;
	}

	/** Initializes or re-initializes reader */
	protected void init () {
		status = STATUS_OK;
		frameCount = 0;
		frames = new Vector<GifFrame>();
		gct = null;
		lct = null;
	}

	/** Reads a single byte from the input stream. */
	protected int read () {
		int curByte = 0;
		try {
			curByte = in.read();
		} catch (Exception e) {
			status = STATUS_FORMAT_ERROR;
		}
		return curByte;
	}

	/** Reads next variable length block from input.
	 *
	 * @return number of bytes stored in "buffer" */
	protected int readBlock () {
		blockSize = read();
		int n = 0;
		if (blockSize > 0) {
			try {
				int count = 0;
				while (n < blockSize) {
					count = in.read(block, n, blockSize - n);
					if (count == -1) {
						break;
					}
					n += count;
				}
			} catch (Exception e) {
				e.printStackTrace();
			}
			if (n < blockSize) {
				status = STATUS_FORMAT_ERROR;
			}
		}
		return n;
	}

	/** Reads color table as 256 RGB integer values
	 *
	 * @param ncolors int number of colors to read
	 * @return int array containing 256 colors (packed ARGB with full alpha) */
	protected int[] readColorTable (int ncolors) {
		int nbytes = 3 * ncolors;
		int[] tab = null;
		byte[] c = new byte[nbytes];
		int n = 0;
		try {
			n = in.read(c);
		} catch (Exception e) {
			e.printStackTrace();
		}
		if (n < nbytes) {
			status = STATUS_FORMAT_ERROR;
		} else {
			tab = new int[256]; // max size to avoid bounds checks
			int i = 0;
			int j = 0;
			while (i < ncolors) {
				int r = ((int)c[j++]) & 0xff;
				int g = ((int)c[j++]) & 0xff;
				int b = ((int)c[j++]) & 0xff;
				tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
			}
		}
		return tab;
	}

	/** Main file parser. Reads GIF content blocks. */
	protected void readContents () {
		// read GIF file content blocks
		boolean done = false;
		while (!(done || err())) {
			int code = read();
			switch (code) {
			case 0x2C: // image separator
				readBitmap();
				break;
			case 0x21: // extension
				code = read();
				switch (code) {
				case 0xf9: // graphics control extension
					readGraphicControlExt();
					break;
				case 0xff: // application extension
					readBlock();
					String app = "";
					for (int i = 0; i < 11; i++) {
						app += (char)block[i];
					}
					if (app.equals("NETSCAPE2.0")) {
						readNetscapeExt();
					} else {
						skip(); // don't care
					}
					break;
				case 0xfe:// comment extension
					skip();
					break;
				case 0x01:// plain text extension
					skip();
					break;
				default: // uninteresting extension
					skip();
				}
				break;
			case 0x3b: // terminator
				done = true;
				break;
			case 0x00: // bad byte, but keep going and see what happens break;
			default:
				status = STATUS_FORMAT_ERROR;
			}
		}
	}

	/** Reads Graphics Control Extension values */
	protected void readGraphicControlExt () {
		read(); // block size
		int packed = read(); // packed fields
		dispose = (packed & 0x1c) >> 2; // disposal method
		if (dispose == 0) {
			dispose = 1; // elect to keep old image if discretionary
		}
		transparency = (packed & 1) != 0;
		delay = readShort() * 10; // delay in milliseconds
		transIndex = read(); // transparent color index
		read(); // block terminator
	}

	/** Reads GIF file header information. */
	protected void readHeader () {
		String id = "";
		for (int i = 0; i < 6; i++) {
			id += (char)read();
		}
		if (!id.startsWith("GIF")) {
			status = STATUS_FORMAT_ERROR;
			return;
		}
		readLSD();
		if (gctFlag && !err()) {
			gct = readColorTable(gctSize);
			bgColor = gct[bgIndex];
		}
	}

	/** Reads next frame image */
	protected void readBitmap () {
		ix = readShort(); // (sub)image position & size
		iy = readShort();
		iw = readShort();
		ih = readShort();
		int packed = read();
		lctFlag = (packed & 0x80) != 0; // 1 - local color table flag interlace
		lctSize = (int)Math.pow(2, (packed & 0x07) + 1);
		// 3 - sort flag
		// 4-5 - reserved lctSize = 2 << (packed & 7); // 6-8 - local color
		// table size
		interlace = (packed & 0x40) != 0;
		if (lctFlag) {
			lct = readColorTable(lctSize); // read table
			act = lct; // make local table active
		} else {
			act = gct; // make global table active
			if (bgIndex == transIndex) {
				bgColor = 0;
			}
		}
		int save = 0;
		if (transparency) {
			save = act[transIndex];
			act[transIndex] = 0; // set transparent color if specified
		}
		if (act == null) {
			status = STATUS_FORMAT_ERROR; // no color table defined
		}
		if (err()) {
			return;
		}
		decodeBitmapData(); // decode pixel data
		skip();
		if (err()) {
			return;
		}
		frameCount++;
		// create new image to receive frame data
		image = new DixieMap(width, height, Pixmap.Format.RGBA8888);
		setPixels(); // transfer pixel data to image
		frames.addElement(new GifFrame(image, delay)); // add image to frame
		// list
		if (transparency) {
			act[transIndex] = save;
		}
		resetFrame();
	}

	/** Reads Logical Screen Descriptor */
	protected void readLSD () {
		// logical screen size
		width = readShort();
		height = readShort();
		// packed fields
		int packed = read();
		gctFlag = (packed & 0x80) != 0; // 1 : global color table flag
		// 2-4 : color resolution
		// 5 : gct sort flag
		gctSize = 2 << (packed & 7); // 6-8 : gct size
		bgIndex = read(); // background color index
		pixelAspect = read(); // pixel aspect ratio
	}

	/** Reads Netscape extenstion to obtain iteration count */
	protected void readNetscapeExt () {
		do {
			readBlock();
			if (block[0] == 1) {
				// loop count sub-block
				int b1 = ((int)block[1]) & 0xff;
				int b2 = ((int)block[2]) & 0xff;
				loopCount = (b2 << 8) | b1;
			}
		} while ((blockSize > 0) && !err());
	}

	/** Reads next 16-bit value, LSB first */
	protected int readShort () {
		// read 16-bit value, LSB first
		return read() | (read() << 8);
	}

	/** Resets frame state for reading next image. */
	protected void resetFrame () {
		lastDispose = dispose;
		lrx = ix;
		lry = iy;
		lrw = iw;
		lrh = ih;
		lastPixmap = image;
		lastBgColor = bgColor;
		dispose = 0;
		transparency = false;
		delay = 0;
		lct = null;
	}

	/** Skips variable length blocks up to and including next zero length block. */
	protected void skip () {
		do {
			readBlock();
		} while ((blockSize > 0) && !err());
	}

	public Animation getAnimation (PlayMode playmode) {
		int nrFrames = getFrameCount();
		Pixmap frame = getFrame(0);
		int width = frame.getWidth();
		int height = frame.getHeight();
		int vzones = (int)Math.sqrt((double)nrFrames);
		int hzones = vzones;

		while (vzones * hzones < nrFrames)
			vzones++;

		int v, h;

		Pixmap target = new Pixmap(width * hzones, height * vzones, Pixmap.Format.RGBA8888);

		for (h = 0; h < hzones; h++) {
			for (v = 0; v < vzones; v++) {
				int frameID = v + h * vzones;
				if (frameID < nrFrames) {
					frame = getFrame(frameID);
					target.drawPixmap(frame, h * width, v * height);
				}
			}
		}

		Texture texture = new Texture(target);
		Array<TextureRegion> texReg = new Array<TextureRegion>();

		for (h = 0; h < hzones; h++) {
			for (v = 0; v < vzones; v++) {
				int frameID = v + h * vzones;
				if (frameID < nrFrames) {
					TextureRegion tr = new TextureRegion(texture, h * width, v * height, width, height);
					texReg.add(tr);
				}
			}
		}
		float frameDuration = (float)getDelay(0);
		frameDuration /= 1000; // convert milliseconds into seconds
		Animation result = new Animation(frameDuration, texReg, playmode);

		return result;
	}

	public static Animation loadGIFAnimation (PlayMode playmode, InputStream is) {
		CHGifDecoder gdec = new CHGifDecoder();
		gdec.read(is);
		return gdec.getAnimation(playmode);
	}
}
